The present invention relates to a wireless article and, in particular, to a wireless article including an antenna having plural turns.
Wireless articles, such as tags, identification badges, smart cards and the like, are in wireless communication with a base unit or reader via a radio-frequency (RF) communication link. RF transmissions transmitted by the base unit may be received by an antenna on the wireless article or RF transmissions transmitted by the wireless article by an antenna thereon may be received by the base unit. Or RF transmissions by each of the wireless article and the base unit may be received by the other one thereof.
In each case, the RF signals either received or transmitted by the wireless article are received or transmitted by an antenna thereon. Because wireless articles are usually desired to be small in size, the antenna thereon must also be small in size. For a loop-type antenna, the sensitivity of the antenna to small amplitude RF signals and the amplitude of the RF signals transmitted by the antenna are a direct function of the area enclosed by the antenna loop and the number of turns of the conductor forming the loop. For a small tag or badge, the size thereof limits the area that an antenna loop can enclose, thereby limiting the RF performance of the antenna.
Antenna RF performance may be improved by increasing the number of turns or loops of conductor that the antenna will have. The terminal at one end of the loop antenna will be outside the loops and the terminal at the other end thereof will be inside the loops. Thus, as more turns or loops are added, the antenna terminals necessarily become spaced further apart. When the loop antenna terminals are to directly connect to an electronic device, adding turns to the antenna soon increases the antenna terminal spacing until it exceeds the distance between the contacts on the electronic device to which the antenna terminals are to connect, thereby necessitating a further degree of undesirably increasing the complexity and cost of the article.
Accordingly, there is a need for a wireless article having a plural-turn antenna that is relatively simple and that can be made relatively inexpensively.
To this end, the present invention comprises a substrate having at least one hole therethrough, an elongated electrical conductor on one surface of the substrate and having at least one end at the hole of the substrate, a pattern of electrically-conductive adhesive on a second surface of the substrate, the electrically-conductive adhesive being electrically connected to the elongated electrical conductor through the at least one hole in the substrate and having at least one contact, and an electronic device attached to the substrate and having at least one contact electrically connected to the contact of the pattern of electrically-conductive adhesive.
According to another aspect of the invention, a method of making a wireless article comprises:
providing a substrate having holes therethrough and an elongated conductor on a first surface thereof having ends of the elongated conductor extending at least partially over the holes;
depositing electrically-conductive material in the holes to electrically connect to the elongated conductor;
depositing a pattern of electrically-conductive adhesive on a second surface of the substrate to electrically connect the elongated conductor to first and second contacts; and
attaching first and second contacts of an electronic device to the first and second contacts of the pattern of electrically-conductive adhesive on the substrate.